Resolving dependencies... cabal: Could not resolve dependencies: trying: prove-everywhere-server-0.1.1 (user goal) trying: base-4.8.1.0/installed-4f7... (dependency of prove-everywhere-server-0.1.1) next goal: optparse-applicative (dependency of prove-everywhere-server-0.1.1) rejecting: optparse-applicative-0.12.0.0, 0.11.0.2, 0.11.0.1, 0.11.0, 0.10.0 (conflict: prove-everywhere-server => optparse-applicative==0.9.*) rejecting: optparse-applicative-0.9.1.1, 0.9.1, 0.9.0 (conflict: base==4.8.1.0/installed-4f7..., optparse-applicative => base>=4 && <4.8) rejecting: optparse-applicative-0.8.1, 0.8.0.1, 0.8.0, 0.7.0.2, 0.7.0.1, 0.7.0, 0.6.0, 0.5.2.1, 0.5.2, 0.5.1, 0.5.0, 0.4.3, 0.4.2, 0.4.1, 0.4.0, 0.3.2, 0.3.1, 0.3.0, 0.2.0, 0.1.1, 0.1.0, 0.0.1 (conflict: prove-everywhere-server => optparse-applicative==0.9.*) Dependency tree exhaustively searched.